Five-time champion Roger Federer is out of the US Open after Bulgaria’s Grigor Dimitrov won a late-night thriller to finally beat the Swiss great.
Federer, 38, had won all seven of their previous meetings but unseeded Dimitrov fought back to win 3-6 6-4 3-6 6-4 6-2.
Federer, who needed treatment for a back injury in the latter stages, said: “I felt it the whole time, but I was able to play.”
Dimitrov, 28, faces Russian fifth seed Daniil Medvedev in the last four.
Meanwhile, Serena Williams underlined her tag as the favourite for the US Open with a brutal quarter-final win over China’s Wang Qiang in just 44 minutes.
The 37-year-old American broke serve five times and hit 25 winners as she eased to a 6-1 6-0 win over the 18th seed on Arthur Ashe Stadium
Williams, seeded eighth, is chasing a record-equalling 24th Grand Slam title.
She will face Ukraine’s fifth seed Elina Svitolina, who beat Britain’s Johanna Konta, in the semi-finals.